Analysis of leakage currents in 1.3-µm InGaAsP real-index-guided lasers

We describe leakage current calculation in several real-index-guided laser structures using an electrical equivalent circuit model. The structures analyzed are different types of buried heterostructures in which heterojunctions are used for lateral carrier confinements. The device types are: 1) the etched-mesa buried heterostructure (EMBH); 2) the channeled-substrate buried heterostructure (CSBH); 3) the double-channel planar buried heterostructure (DCPBH); 4) the planar buried heterostructure (PBH); and 5) the buried crescent (BC). Adequate current confinement is necessary in a laser structure for both linearity and low threshold operation. Thus leakage current, i.e., the difference between the injected current and the current through the active region, should be small. We have identified the main leakage paths in these structures and the parameters (the relevant layer thicknesses and doping levels) that determine the magnitude of the leakage current. The effect of nonradiative recombination sites on junction parameters and the consequent increase in leakage current is discussed.